The use of thresholds in residential and commercial buildings is an integral part of conventional construction. External doors are most effectively mounted in conjunction with a lower plate or threshold member above which the door may be oriented in a closed position. The threshold may serve multiple functions. For example, the threshold reduces a distance between a surface above which the door swings and a bottom of the closed door. The threshold may also function as a barrier to air and moisture infiltration. In some designs, sealing members are incorporated with the door to reduce or substantially eliminate moisture infiltration under the closed door.
In certain applications, a threshold for a doorway may need to meet certain design requirements. For example, the Americans with Disabilities Act (“ADA”) sets forth certain requirements for thresholds to minimize an impact a threshold might have on a person having disabilities ability to pass through the doorway. One such requirement is to reduce a height of the threshold relative to a walking surface upon which the threshold is installed. In order to maintain a low height difference between the threshold and the walking surface, prior thresholds have required modification of the walking surface. For example, the walking surface may either be raised to abut edges of the threshold or a portion of the walking surface may be cut out and removed to form a groove or trough for the threshold to sit in. Incorporating a threshold system using either of these ways can lead to problems. For example, it can be difficult to provide a seal to prevent water from accumulating underneath the threshold. Accumulated water can induce other problems like mildew or mold. Furthermore, for some walking surfaces it may not be desirable or permitted to modify the walking surface with cuts and the like. Therefore, a threshold system that complies with requirements of the ADA, is installable with minimal alteration of the walking surface, and provides an accessible seal to prevent water from accumulating underneath the threshold is desirable.